James h



(No Model.)

J.H.ROBERTSON.

TELEPHONE.

-N0. 329,084. Patented Oct. 27, 1885.

re PETERS. Mammogram, Wuhhgion. n. r.

UNITED STATES PATENT OFFICE.

JAMES H. ROBERTSON, OF BROOKLYN, NEW YORK.

TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 329,084, dated October 27, 1885.

Application filed February 14, 1883. Renewed Mai-ch20, 1885. Serial No. 159,583.

To a. whom, it may concern.-

Be it known that I, JAMES H. ROBERTSON, of the city of Brooklyn, in the county of Kings and State of New York, have invented an Improvement in Speaking-Telephone Receivers, of which the following is aspecification, refer ence being had to the accompanying drawing, forming part thereof, the said drawing being a side View, partly in section, of the receivinginstrument of a telephone containing my invention.

On the 10th of February, 1883, I filed in the Patent Office an application for a patent for improvement in telephones, in which I have described and claimed substantially the same organization which I herein describe, with the exception of the permanent magnet which I now introduce into said organization for the purpose specified, thereby forming anew combination, to which new combination I intend in this specification to limit my claim. Iwill,

however,proceed to describe the entire instrument in which my present improvement is embodied, including the devices set forth in the specification above referred to as filed February 10, 1883.

The drawing is a side elevation, partly in' section, of a telephone containing my improvements. The lower portion of the same rep resents a telephone-transmitter consisting of a diaphragm, H, properly mounted, (the mounting not shown,) a free vibrating electrode, l, in the primary circuit of an induction-coil, J, being a battery, the pole-wires a a of which constitute said circuit, and K K, respectively, the primary and secondary helices of said induction coil. The secondary circuit-wire c is grounded at its ends, and extends from the said induction-coil to the receiver, as shown. The upper part of the figure represents my receiver, in which A is the coil of an electro-magnet in the secondary cir-' cuit of the described induction-coil, and the core B of said magnet, which is preferably made hollow and fitted in its outer end with a screw-p1ug,0. This plug worksin a female screw-thread in the core. 9 is a spiral spring, which is located in the opposite end of the core, and carries on the outer end an armature, E, from the outer face of which projects an electrode, b. This spring is to be so adjusted by means of the screw-plug O that the (No model.)

electrode b will be normally in contact with the electrode 1) on the diaphragm.

D is the tympanum or diaphragm, mounted in the usual way, and carrying at its center an electrode, b. When, however, the diaphragm itself is made of a material that is a conductor of electricity, the electrode may be made to impinge directly on the diaphragm itself without any projection thereon such as the electrode b, shown in the drawing.

The course of the secondary circuit is, as shown, from the coil K in the transmitter that is grounded, as shown, to coilAin the receiver; thence through core B, electrode 1), and diaphragm D to ground through wire 0. When anon-conducting material is used for the diaphragm, an electrode, 1), is secured to the diaphragm for contact with the electrode b, and the wire a may run directly from the electrode b to ground. The electrodes may be either of metal or carbon.

By the described arrangement of parts, the secondary circuit of an induction-coil in the primary circuit of which is the transmitter, the secondary circuit being so arranged that the induced current passes through vibrative electrodes as well as the helix of the receiving-magnet, whereby the change produced in the primary current by the vibrations of the transmitting-diaphragm are accompanied by simultaneous changes'in the secondary current produced by the corresponding changes in the receivingdiaphragm, I find that the reproduction of articulate speech at the receiver is improved.

The instrument as thus far described is substantially similar to that described and shown in the specification and drawings filed with my application for a patent February 10, 1883, before referred to. To such instrumentlhave added the improvement which I intend here to claim.

The improvement consists in the combination, with the above-described parts of the receiver, of an auxiliary permanent magnet, which co-operates with the magnetism developed by the secondary current, whereby continuous tension due to the attraction of the permanent magnet is given to the spring g,- and I find that by this means the articulation at the receiver is still further improved.

Gis the permanent steel magnet, to one end of which is secured the soft-iron core B, wherecontact and regulated by the screw-plug and spring. The spring at the same time holds the armature E away from contact with the pole of the core B, while the permanent magnetic force of said core acts to draw the armature toward the core against the stressof the spring and thus gives a permanent tension to the spring. Thus there is secured to the auxiliary cooperation of the permanent magnet on the armature E with the magnetism developed by the secondary current, which, together with the resistance at the electrodes 1) 1), simultaneously reproduces at said electrodes of the receiver all changes made at the contact-points in the transmitter, (as in the telephone described and shown in Letters Pat ent N0. 289,309, of November 27, 1883,) and moreperfectly reproducing in the diaphragm of the receiver the vibrations of the transmitting-diaphragm by reason of the describedcooperation of the permanent magnet, whereby the articulation at the receiver is improved.

What I claim, and desire to secure by Letters Patent, is-

1. The combination of the permanent magnet G, the core B in a telephone-receiver comprising the said core, the coil A, diaphragm 5 D, electrode 12 on the said diaphragm, and the electrode bon thearmature Ein the secondary circuit of an induction-coil, in the primary circuit of which is the transmitter, all arranged as described, whereby the secondary current 40 passes through the said electrodes and the said core is polarized by the said permanent magnet, as and for the purpose specified.

2. In a speaking-telephone, the diaphragm, the actuating-magnet having a hollow core, 45 an armature arranged in front of the pole of said magnet, so as to be actuated thereby, and carrying a contactpoint in contact with the diaphragm, and a spring in the said core, arranged as described, to control the contact be- 50 tween said contact-point and the diaphragm,

as set forth.

JAMES H. ROBERTSON. In presence of P. B. VERMILYA, A. G. N. VEnMrLYA. 

